1. Field of the Invention
The present invention relates to a thrust roller bearing and more particularly, to a thrust roller bearing used in a compressor for a car air conditioner, an automatic transmission, a manual transmission, a hybrid car and the like.
2. Description of the Background Art
A conventional thrust roller bearing 101 used in a compressor for a car air conditioner, an automatic transmission, a manual transmission, a hybrid car and the like is disclosed in Japanese Unexamined Patent Publication No. 2003-83333, for example. Referring to FIG. 7, the thrust roller bearing 101 disclosed in this document comprises a plurality of rollers 102, a track ring 103 holding the plurality of rollers in the axis direction and a cage 104 retaining the plurality of rollers 102.
In addition, the cage 104 has a pair of ring parts 104a and 104b and a plurality of pillar parts 104c formed between the ring parts 104a and 104b, and a pocket 104d holding the roller 102 is provided between the adjacent pillar parts 104c. The pillar part 104c forming the pocket 104d is bent into approximately M shape, in which stopper parts 104e are located on one side and the other side in the thickness direction of the cage 104 to hold the roller 102 and a guide part 104f is located between the adjacent stopper parts 14e to guide the rolling surface of the roller 102.
Here, according to the cage 104 used in the conventional thrust roller bearing 101, when it is assumed that the distance between the outer wall surface of the pocket 104d in a diameter direction and the guide part 104f positioned outside in the diameter direction is l1, and the distance between the inner wall surface of the pocket 104d in the diameter direction and the guide part 104f positioned inside in the diameter direction is l3, it is set such that l1=l3 in general.
Recently, the compressor for the car air conditioner, the automatic transmission, the manual transmission, the hybrid car and the like have been further miniaturized and powered up, and the thrust roller bearing incorporated in those is desired to correspond to high speed. Meanwhile, since the lubricant oil amount is reduced for low-fuel consumption in view of environments and the lubricant oil having low viscosity is used, the thrust roller bearing is used under increasingly harsh conditions. Therefore, the wear (drilling wear) generated at the contact part between the outer end face of the roller in the diameter direction and the pocket wall surface at the time of bearing rotation has become a problem.